CORS error while trying to login using SAML

I have a node/express server running on port 3000 that uses @node-saml/passport-saml library to implement SAML-based SSO where the IPD is auth0. Below are the code snippet screenshot. Everything works fine when I hit the /user/saml/login route from the browser. If the user is not logged in, I am getting an auth0 login screen to log in and afterwards things are as expected. However, I have an Angular app that is running on port 4200 which is supposed to hit the /user/saml/login URL. But when I try to hit the same it is throwing the below CORS error. I do understand that I need to whitelist all the domains but not sure where I need to register them and I have tried a couple of things, but none seems to work. Can anybody help me to fix the issue?

Access to XMLHttpRequest at 'https://*********' (redirected from 'http://localhost:3000/api/user/saml/login') from origin 'http://localhost:4200' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource.